Adaptive Importance of Mesocotyl and Coleoptile Growth in Rice Under Different Moisture Regimes.

1978 ◽  
Vol 5 (4) ◽  
pp. 511 ◽  
Author(s):  
N Takahashi
Keyword(s):  
Moisture Content ◽  
Adaptive Response ◽  
Optimum Moisture Content ◽  
Ethylene Formation ◽  
Coleoptile Growth ◽  
Moisture Regimes ◽  
Mesocotyl Elongation ◽  
Endogenous Ethylene ◽  
Water Tension ◽  
Submerged Conditions

The lengths of mesocotyls (first internodes) and coleoptiles of rice varied greatly with the moisture content of the seed-bed. The optimum moisture content in most Indica cultivars was much higher for coleoptile than for mesocotyl growth, but not in some Japonica cultivars because the mesocotyl growth was not vigorous and did not vary with water content. Under submerged conditions, coleoptile growth was markedly stimulated, particularly in Japonica cultivars but there was no mesocotyl elongation in either cultivar. The plastic variability in the growth of coleoptile, leaves, mesocotyl and other internodes may be an adaptive response of rice to the water tension of the soil. Endogenous ethylene formation and effects of ethylene and carbon dioxide were also studied.

Temporal change in wood quality attributes in standing dead beetle-killed lodgepole pine

2008 ◽  
Vol 84 (3) ◽  
pp. 392-400
Author(s):  
Steen Magnussen ◽  
Dave Harrison
Keyword(s):  
Moisture Content ◽  
Wood Quality ◽  
Basal Area ◽  
Wood Moisture ◽  
Moisture Regimes ◽  
Standing Dead ◽  
Blue Stain ◽  
Lodgepole Pines ◽  
Ring Analysis ◽  
One Year

The number and size of checks, wood moisture content, extent of blue-stain, rot and decay was examined by stem analysis in 360 mature standing beetle-killed lodgepole pines. Trees came from three areas (Burns Lake, Quesnel, and Vanderhoof) in Central British Columbia. Each area was represented by 14 to 16 sampling areas (stands) distributed evenly across three soil moisture regimes (dry, mesic, wet). Year of death was estimated from tree ring-analysis, local knowledge and insect and disease survey maps. An approximately equal number of trees had been dead for one or two years, three or four years, or for five or more years. During the first five years since death by beetle attack the number of checks per tree increased from 2.5 to 10.2 and the average depth of checks increased from 4.3 cm to 5.1 cm. Checks were deeper, wider, and longer on the drier sites than on mesic and wet sites. Moisture content of sapwood and heartwood was near the fibre saturation point (ca 30%) one year after death and continued to decrease at a rate of approximately 1.7% per year. Both the incidence and the extent (relative to basal area) of rot and decay increased significantly with time since death. All trees had an extensive blue-stain discoloration. Deterioration of wood quality was fastest during the first two years after a beetle attack. Key words: wood checks, moisture content, blue-stain, wood quality, spiral grain, bark beetle

scholarly journals Effect of Sand Percentage on the Compaction Properties and Undrained Shear Strength of Low Plasticity Clay

2021 ◽  
Vol 9 (1) ◽  
pp. 16-20
Author(s):  
Iyad Alkroosh ◽  
Ali Al-Robay ◽  
Prabir Sarker ◽  
Saif Alzabeebee
Keyword(s):  
Shear Strength ◽  
Moisture Content ◽  
Undrained Shear Strength ◽  
Optimum Moisture Content ◽  
Dry Density ◽  
Sand Content ◽  
Compression Tests ◽  
Maximum Dry Density ◽  
Sand Mixture ◽  
Undrained Shear

This paper investigates the influence of sand content on the mechanical behavior of a low plasticity clay that collected from south of Iraq (Sumer town). Samples have been prepared with sand contents of 0%, 10%, 20%, 30%, and 40% of the clay weight. Standard Proctor and unconfined compression tests have been carried out and the optimum moisture content, maximum dry density, and undrained shear strength have been determined. The results show a gradual increasing trend of the maximum dry density with the increase of the sand content up to 30%. The highest dry density reaches 1.90 g/cm3 corresponding to an optimum moisture content of 12%. In addition, this paper shows that the undrained shear strength is inversely proportional to the increase of the percentage of sand. The results of this work provide a useful addition to the literature regarding the behaviour or low plasticity clay-sand mixture.

Utilization of Large-Scale Rolling-Wheel Tester to Investigate the Stress Reduction in Pavement Layers Due to the Use of Geosynthetic Materials

2019 ◽  
Vol 2673 (2) ◽  
pp. 445-455
Author(s):  
Jason Wright ◽  
S. Sonny Kim ◽  
Mi G. Chorzepa ◽  
Stephan A. Durham
Keyword(s):  
Moisture Content ◽  
Large Scale ◽  
Pressure Sensors ◽  
Optimum Moisture Content ◽  
Small Scale ◽  
Wheel Load ◽  
Subgrade Soils ◽  
Rolling Wheel ◽  
Aggregate Base ◽  
Pavement Foundation

In a geosynthetic-reinforced pavement system, the load-bearing capacity of subgrade soil is improved by the lateral distribution of vertical stresses at the reinforcing layer. Under small-scale triaxial testing, the tensile properties of the geosynthetic are difficult to measure. Therefore, it is desirable to conduct large-scale testing to accurately monitor the behavior of geosynthetic-reinforced pavement foundations when subjected to rolling-wheel loadings. This study investigates the behavior of geosynthetic-reinforced pavement foundation systems through large-scale rolling-wheel tests performed with problematic subgrade soils found in north Georgia. Sixteen large-scale specimens were constructed of which twelve were reinforced with geosynthetic. Subgrade soils were compacted either at their optimum moisture content or at a higher than optimum moisture content to produce different California Bearing Ratios during specimen preparation. Both an extruded biaxial geogrid and woven geotextile were placed at various locations to investigate the optimal placement locations for different subgrade conditions. Pressure sensors were installed near the bottom of the aggregate base layer and near the top of the subgrade layer to monitor the variations in vertical stress within the pavement system under rolling-wheel load. Further, light weight deflectometer measurements were collected post-test to determine the effect of the geosynthetic on pavement foundation stiffness. The vertical pressure at the bottom of the aggregate base and top of subgrade decreased on average approximately 15.3% and 18.8%, respectively. The results indicate which type of geosynthetic and placement location provides the greatest reduction of pressure for each of the given subgrade conditions.

Factors determining the optimum moisture content (OMC) of greywacke aggregates from northern New Zealand

2019 ◽  
Vol 19 ◽  
pp. 35-43
Author(s):  
Wentao Li ◽  
Douglas J. Wilson ◽  
Tam J. Larkin ◽  
Philippa M. Black
Keyword(s):  
New Zealand ◽  
Moisture Content ◽  
Optimum Moisture Content

Compaction Characteristic of Lime Modified Expansive Soil

2013 ◽  
Vol 710 ◽  
pp. 348-351
Author(s):  
Zheng Rong Zhao ◽  
Lei Wang ◽  
Hong Xia Yang
Keyword(s):  
Moisture Content ◽  
Expansive Soil ◽  
Size Composition ◽  
Optimum Moisture Content ◽  
Dry Density ◽  
Content Increase ◽  
Maximum Dry Density ◽  
Compaction Curve ◽  
Compaction Characteristic ◽  
Two Peaks

Through compaction test discussed about the compaction characteristics of expansive soil by lime modified in middle of Shandong province. The results show that the optimum moisture content is lower when the expansive soil is cured by dry compaction method, and the maximum dry density is higher. Compaction curve appeared the phenomenon of two peaks when expansive soil is cured by wet compaction method.Lime content of lime improved expansive soil, particle size composition, age and compaction function have influence on compaction curve.With the increase of the quantity of lime, the optimum moisture content increases, the maximum dry density decreases. With the age growth, the optimum moisture content increase slightly,the maximum dry density decreases slightly. The bigger the compaction work, the smaller moisture content is, the larger the maximum dry density is.

scholarly journals Modeling the Resilient Modulus Variation of In Situ Soils due to Seasonal Moisture Content Variations

2019 ◽  
Vol 2019 ◽  
pp. 1-7
Author(s):  
Kevin Gaspard ◽  
Zhongjie Zhang ◽  
Gavin Gautreau ◽  
Khalil Hanifa ◽  
Claudia E. Zapata ◽  
...  
Keyword(s):  
Moisture Content ◽  
Resilient Modulus ◽  
Optimum Moisture Content ◽  
Test Method ◽  
Large Scatter ◽  
Controlling Parameter ◽  
Base Course ◽  
The Relationship ◽  
Level 2

LTRC is conducting a research project to determine the seasonal variation of subgrade resilient modulus (MR) in an effort to implement PavementME. One objective of that project, which is presented in this paper, was to locally calibrate the Enhanced Integrated Climate Model’s (EICM Fenv) curve for seasonal subgrade MR changes. Shelby tube sampling was conducted on six different roadways to a depth of approximately 7.92 m beneath the shoulder pavement’s base course. The AASHTO T-99 MR test method was used on all samples with an additional eight specimens being tested with NCHRP 1–28A MR test method. Four soils from Louisiana which were not from the six roadways were also tested and included in the analyses. Once the MR tests were completed and plotted, it was noticed that there was a rather large scatter (R2 = −0.266) around the EICM Fenv curve. The authors hypothesized that this occurred due to the density differences between in situ and remolded specimens. Further analyses confirmed this hypothesis. LTRC developed a new method based on the EICM Fenv method to determine the relationship between changes in subgrade MR as a function of changes in moisture content with the in situ moisture content and MR used as the control. This method differs from the EICM Fenv in that the EICM Fenv uses optimum moisture content as the controlling parameter. The LTRC method can be used for design purposes as well as level 2 inputs into the EICM.

Optimum moisture content in roller-compacted concrete pavement

2019 ◽  
Vol 21 (14) ◽  
pp. 1769-1779 ◽  
Author(s):  
Payam Shafigh ◽  
Mohammad Hashemi ◽  
Boo Hyun Nam ◽  
Suhana Koting
Keyword(s):  
Moisture Content ◽  
Optimum Moisture Content ◽  
Concrete Pavement ◽  
Roller Compacted Concrete
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